Flotation apparatus



Aug. 11, 1953 A. ZARN FLOTATION APPARATUS 2 Sheets-Sheet 1 Filed NOV. 22, 1949 INVENTOR 1900a PHE ZHRN ATTORNEY Aug. 11, 1953 A- ZARN FLOTATION APPARATUS 2 Sheets-Sheet 2 Filed Nov. 22, 1949 I INVENTOR I 6004p: 219R ATTORNEYS Patented Aug. 11, 1953 FLOTATION APPARATUS Adolphe Zarn, Zurich, Switzerland, assignor to Societe J aruza A. G. Chur, Zurich, Switzerland,

a Swiss company Application November 22, 1949, Serial No. 128,697 In Belgium November 23, 1948 6 Claims. (Cl. 209-468) This invention relates to flotation apparatus and "has more particular reference to flotation machines of the mechanical agitation type, such as are commonly employed in concentrating ores and other material.

One object of the present invention is to provide a novel and improved flotation machine including a series of adjacent cells placed one behind the other in a vat bearing in its longitudinal axis a single revolving shaft and stirrers keyed on the shaft, one in each cell.

Another object of the invention is to provide a flotation machine, as above characterized, wherein each cell comprises a stirring compartment and a separation compartment.

Another object of the invention is to provide a flotation machine, as above characterized, wherein a diffusing crown, in the form of a shock-proof iron sheet, surrounds the stirrer in each cell and wherein the separation compartment of each cell is provided with an anti-eddy water-grate.

Another object of the invention is to provide a flotation machine, as characterized above, wherein each cell is provided with a foam evacuating duct extending transversely thereof above the stirring compartment and wherein separate means are provided to supply air to each stirrer.

A further object of the invention is to provide a flotation machine, as above characterized, which is simple in construction, low in cost of manufacture, and efficient in operation.

Other objects and advantages of the invention will appear in the following specification when considered in connection with the accompanying drawings, wherein:

Fig. l is a longitudinal vertical sectional v ew of a preferred embodiment of a flotation mach ne constructed in accordance with the present invention;

. Fig. 2 is a vertical sectional view taken on the line 2-2 of Fig. 1; and

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 1.

Referring now to the drawings, there is shown, in Figs. 1, 2 and 3, one embodiment of a flotation machine constructed in accordance with the present, invention and comprisin .a box-like tank or vat It having a semi-cylindrical base or bottom wall ll, side walls 12 and i3, and end walls [4 and 15; said vat being divided into a series of connected or communicating cells l6, l7 and i8; and a tailings discharge and level regulating unit, indicated generally at 19. Any number of intermediate cells ll may be interposed in series 2 between the end cells it and 18, but, for con venience of description, only one such interme. diate cell is shown.

The vat is partitioned into the several cells partition wall in conjunction with the end wall 15, the side walls 12 and I3, and the bottom wall ll. As shown, each of the partition walls 20 is provided with a narrow, rectangular opening 2i through which the pulp may readily pass from one cell to the next. The tailings discharge and level regulating unit I9 is located at the dis charge end of the apparatus, as viewed at the right in Fig. 1. This unit is formed by the end wall 85 of the vat in conjunction with a vertical end wall 22, an inclined bottom wall 23, and Side walls formed by extensions of the side walls l2 and E3 of the vat. The tailings or residue from the end cell 18 pass into this unit through an elongated opening 24 in the end wall I5 of the vat.

The end wall 22 of this unit is provided with a weir 2,5, the height of which ma be controlled by the number of superimposed slats 26, whereby he desired dep h of pulp may .be maintained in the vat. The tailings overflowing the lip of the weir discharge into a trough or launder ,2? which extends transversely of the unit.

Each of the three cells is generally similar in construction and each is provided with a stirring device 23 mounted on a shaft 29 which extends longitudinally through the vat. The shaft 29 is suitably journaled in bearings carried by the partition walls 20 and the end walls of the vat. The shaft 29 may be rotated by any suitable means; in the particular embodiment illustrated, the outer right hand end .of the shaft, as viewed in Fig. 1 is shown as carrying a gear 30 adapted to be connected with and driven by a drive gear, not shown. Each of the stirring devices 28 is shown as comprising a hub 3i keyed on the shaft 29 and carrying a pair of elongated stirring blades 32 having their faces lying in planes substantially parallel to the longitudinal axis of the shaft 29, and a pair of short impeller blades 33 having their faces lying in planes extending obliquely and transversely of tical end walls 35, 36 extending transversely of the vat and secured along their bottom and side edges to the bottom and side walls of the vat,

and a top wall 3'! sloping downwardly from the end wall 36 to the end wall 35, or to the left as viewed in Fig. l. Preferably, and. as shown, each of the stirring devices is also encircled by a diffusing crown in the form of an annular member 38 mounted within the housing 34. The member 38 is preferably made of sheet iron.

The housing 34 is provided with a circular intake opening 39 and a circular discharge opening 46, both concentric with the shaft 29. The discharge opening 46 of the housing is shown as being provided with a screen or grid 4| made up of vertical blades 42 and horizontal and downwardly slanting blades 43, so arranged that the passageways formed by the blades slant downwardly and to the right, as viewed in Fig, 1. Each of the grids 41 may carry a bearing for the shaft 29.

Each of the cells is provided with a vertical transverse wall forming member 44 which is secured to the side walls l2 and i3 and extends downwardly into the cell to a point below the top of the housing 34, with the wall forming member 44 spaced from the end wall 36 of the housing, as shown in Fig. l. The vertical end wall 36 of the housing 34 and the wall forming member 44 form a wall dividing the cell into two compartments; a stirring compartment in which the pulp is agitated by the stirring device, and a froth separating compartment in which the agitated pulp is forced by the stirring device through the grid 4| and in which the froth and intermediate products are separated from the heavier or sinking products. The space between the vertical end wall 36 of the housing 34 and the wall forming member 44 forms a passageway 45 connecting the upper portions of the two compartments, for a purpose hereinafter to be described.

The flow of material through the passageway 45 may be controlled, as by means of a vertically adjustable sluice gate 45 slidably mounted in suitable guide bars 41 secured to the side walls l2 and I3 of the vet. The sluice gates may be raised and lowered by any suitable mechanism, in the particular embodiment of the invention illustrated, the sluice gates are shown as having a pair of spaced racks 48 secured thereto and adapted to be driven by pinions 49 fixedly mounted on a shaft 56. The shaft 50 extends transversely of and is suitably journaled in the side walls of the vat and has a projecting end adapted to be connected to and operated by any suitable mechanism (not shown).

In a similar manner, the flow of material through the openings 2l in the cell partition walls 26 may be controlled by vertically adjustable sluice gates 52 carrying racks 53 operated by pinions 54 fixedly mounted on a shaft 55 which extends transversely of the vat.

To prevent the bottom of the stirring compartment in each cell I1 and I8 from acting as a depository for solid material, a wall member 56 is secured therein with its end edges secured to the side walls l2 and E3 of the vat and its upper longitudinal edge secured to the end wall 35 of the housing 34, and its lower longitudinal edge secured to the vertical partition 26, the lower longitudinal edge engaging the partition 2! along the bottom edge of the opening 2i, as shown in Fig. 1. The inclined wall member 56 also serves to direct the material passing through the opening 2! in the wall 26 upwardly to the intake opening 39 in the housing 34.

The froth separating compartment in each cell is divided into an upper and lower part by means of an anti-eddy water-gate or strainer 51 which is shown as being formed by a pair of vertically spaced perforated plates 58 extending transversely of the cell and between the housing 34 and the end wall of the cell immediately above the discharge opening 40 of the housing.

The pulp agitating or stirring compartment in each of the cells I6, I! and I8 and the tailings discharge and level regulating unit 19 are closed at their upper ends in a manner to form a transversely extending froth removing trough over each of their upper ends.

The stirring compartment in cell I6 is shown as being closed at its upper end by a horizontal wall forming member 55 secured along one longitudinal edge to the top of the end wall [4, and at its ends to the side walls [2 and 13 of the vat, a vertical transverse partition 66 extending between and secured to the side walls 12 and [3 of the vat and secured along its bottom edge to the other longitudinal edge of the member 59; and an inclined wall member 6| secured at its upper end to side wall 13 of the vat, at its lower end to side wall #2 of the vat, and along its longitudinal edges to the vertical transverse wall member 66 and the vertical transverse wall member 44 in the cell IS. The inclined member 6| and the upper end portions of the members 50 and 44 form a trough 62 extending transversely of the vat.

The stirring compartment in cell I1 is shown as being closed at its upper end by an inclined wall member 63, secured at its upper end to side Wall l3 of the vat, at its lower end to side wall 12 of the vat, and along its longitudinal edges to the vertical transverse partition wall members 20 and 44 which form the upper side walls of the stirring compartment of cell IT. The inclined member 63, and the upper end portions of the vertical members 20 and 44 form a trough 64 extending transversely of the vat.

The stirring compartment in cell 18 is shown as being closed at its upper end by an inclined wall member 65, secured at its upper end to side wall l3 of the vat, at its lower end to side wall l2 of the vat, and along its longitudinal edges to the vertical transverse partition wall members 26 and 44, which form the upper side walls of the stirring compartment of cell l 8. The inclined member 65 and the vertical members 20 and 44 form the bottom and side walls, respectively, of a trough 66 extending transversely of the vat. The upper end of the level regulating unit I9 s shown as being closed at its upper end by an inclined wall member 67 secured at its upper end to side wall l3 of the vat, at its lower end to side wall [2 of the vat, and along its longitudinal edges to the end wall [5 of the vat and end wall 22 of the level regulating'unit. The inclined member 6?, and the upper end portions of the vertical end wall members l5 and 22 form a trough 68 extending transversely of the vat.

The froth separating compartment in each cell 18 open at its upper end and the froth is removed therefrom, as by means of a pair of horizontally spaced skimming devices 69. The skimming devices are identical in construction and each is shown as comprising a pair of concave skimmers 10 secured to a shaft ll extendmg transversely of the vat and journaled in bearings formed in suitable supports mounted on the side walls of the vat. The shaft H is shown as being provided at one end with "a pulley 12 adapted to be connected with and driven by a drive pulley (not shown), The pulleys in each pair are designed to rotate in opposite directions, as shown by the arrows in Fig, 1, so that the shimmers will force the foam over the upper edges or lips of the vertical partition walls defining the rroth separating compartments, into the respective ones or its troughs B2, 64, 66 and 58, adjacent thereto. The troughs 62, 64, 6'6 and 68 extend transversely of the vat and discharge through openings 13 formed in the side wall 12 of the vat in alignment with the troughs, into a collecting trough 14 extending along the upper outer part or the side wall 12 of the vat. The trough 14 slopes downwardly to theleft, as viewed in Fig. l, to provide for gravity flow.

The pulp is fed into the cells through valved branch conduits '15 connected to a manifold 16, which, in turn, is connected to the source or supply of pulp (not shown). The pulp supply conduits extend into the cells through cylindrical housings 11 which extend through and are secured to the inclined wall members forming the bottoms of the froth removing troughs. The outlet ends of the branch conduits are positioned to discharge the pulp into the upper part of the stirring compartment in the cells. The reagent of flotation preferably is fed into the cells together with the raw pulp through the pulp supply conduits.

Each of the cells is provided with the air necessary for the flotation process by means of valved branch air pipes 18 connected to an air manifold I9, which, in turn, is connected to a source of air supply (not shown). The branch air pipes 78' extend down into the vat and are connected to nozzles 80, secured to the walls of the cells. The nozzles 81] surround the shaft 29 with their closed ends forming bearings for the shaft and their open ends positioned to discharge the air into the stirring compartment of the cells at a point closely adjacent to and concentric with the intake openings 39 of the housings 34. Each of the air supply pipes 18 is provided with a throttle valve 8| to control the flow of air into the cell.

Each of the cells I6, I! and I8 is shown as having a valve conduit 82 connected to the bottom of the froth separating compartment therein, by means of which any solid material therein may be removed. The launder 2'! is also shown as having a drain pipe 83 connected thereto.

In the operation of the machine, the pulp to be treated, together with the reagent, is admitted to any one or all of the cells through the valved branch pulp feed conduits and is delivered into the pulp agitating or stirring compartment in the cell.

The air necessary for flotation is delivered to a point adjacent the inlet opening of the stirrer housing in each cell through the valved branch air pipes 18 and nozzles 80.

The stirrer sucks the air, pulp and reagent mixture into the stirrer housing through the inlet openings therein. Here the mixture is thoroughly agitated and aerated and discharged through the grids on the outlet opening of the stirrer housing downwardly into the lower part of the froth separating compartment of the cells. Here, the sinking product can either be evacuated through the valved conduits 82, or sucked into the next cell, by the stirrer therein, through the openings 2 I in the partition walls 20.

In the last cell In, the sinking products may be evacuated through the valved conduit 82, or may pass with the tailings through the opening 24 in the end wall of the vat into the tailings discharge and level regulating unit I9, from which they discharge into the launder 21.

The foam and intermediate products rise up through the anti-eddy water strainers 51 into the upper part of the foam separating compartment, where the intermediate products are recycled back inc the stirring compartment through the passageway 45 and the foam, after rising to the top of the compartment, is pushed by the skimmers into the transverse troughs B2, 64, 66

' and 68 which empty into the collecting trough In connection with the foregoing, it should be noted that the impeller blades of the stirrers are designed to circulate the pulp through the cells while the stirrer blades thoroughly agitate the pulp.

It should also be noted that each cell supplies three products:

(1) Foam ejected into the collecting trough and which can be sent back into any of the cells, if desired, by suitable conduits (not shown).

(2) Intermediate products which are passed back into the stirring zone of the cells, and

(3) Sinking products which can be evacuated from the cell through the valved conduit 82 or sucked by the stirrer of the next cell through the opening in the partition 20 below the nozzle 8'0.

While the machine has been illustrated as having only one shaft carrying a stirring device for each cell, obviously, the cells may be made wide enough to provide a plurality of parallel shafts supporting parallel stirring devices in each cell.

Obviously, too, the invention is not limited to any particular number of cells. As few as one only may be employed, which single cell maybe associated with the tailings discharge and level regulating unit 19, as will readily be understood from the foregoing description.

Obviously, also, the invention is not restricted to the particular embodiment thereof herein shown and described. Moreover, it is not indispensible that all of the features of the invention be used conjointly, since they may be employed advantageously in various combinations and subcombinations.

What is claimed is:

1. Flotation apparatus comprising an elongated vat having side, and and bottom walls, a plurality of laterally spaced partition walls extending upwardly from the bottom of the vat and from side to side thereof dividing thevat into a plurality of alternate pulp receiving and froth separating compartments, each of said partition walls having an opening formed therein adjacent its bottom end for the passage of pulp; conduits for supplying pulp and air to the first of said pulp receiving compartments; a rotatable shaft extending longitudinally of the vat and having a plurality of rotatable stirrers fixed thereon, one in each pulp receivin compartment, each of said stirrers having blades shaped and positioned to agitate and aerate the pulp and force it into the adjacent froth separating compartment; housing means around each of said stirrers to confine its agitating and aerating action to the space therein; screen members in the froth separating compartments above said openings to prevent turbulence in the upper portions of said separating compartments; means, including troughs, for evacuating the froth from each of said froth separating compartments; and means, including a conduit, for withdrawing the t'ailings from the last of said froth separating compartments, the construction and arrangement being such that, as the pulp moves through the vat, it'will pass through in succession, a series of alternate pulp receiving compartments and froth separating compartments, so that it will be successively agitated and aerated by the stirrers in the pulp receiving compartments and maintained in a quiescent state in the froth separating compartments.

2; Flotation apparatus, as set forth in claim 1, wherein each of the walls separating a froth separating compartment from its adjacent, preceding pulp receiving compartment is provided with an opening adjacent its upper end to permit pulp to flow from the upper end portion of the froth separating compartment into the upper end portion of the adjacent, preceding pulp receiving compartment. I 3. Flotation apparatus, as set forth in claim 1 wherein downwardly inclined louvers are mounted across the openings in the walls separating each of the froth separating compartments from its adjacent, preceding pulp receiving compartment to direct the pulp discharged from the pulp 1eceiving compartments downwardly at an angle into the bottoms of the froth separating compartments.

4. A flotation cell having side, end and bottom walls, an intermediate wall extending upwardly from the bottom of the cell and from side to side thereof dividing the cell into a pulp receiving compartment and a froth separating compart ment, both extending across the entire width of the cell, said intermediate wall having an open ing therein adjacent to its bottom end for the passage of pulp; conduits for supplying pulp and air to said pulp receiving compartment; a rotatable shaft extending longitudinally of said cell and through said opening in said intermediate wall; a rotatable stirring device fixed on said shaft and positioned in said pulp receiving compartment adjacent to said intermediate wall, said stirring device having blades shaped and posi tioned to agitate an aerate the pulp therein and force it through the opening in said intermediate wall into said froth separating compartment; housing, means around said stirrer to confine its agitating and aerating action to the space therein; a screen member in the froth separating compartment above said opening to prevent turbulence in the upper portion of said separating compartment, means, including a trough, for evacuating the froth from said froth separating compartment; and means, including a conduit, for withdrawing the tailings from said froth separating compartment.

5. A flotation cell, as set forth in claim 4. wherein said intermediate Wall is provided with an opening adjacents its upper end to permit pulp to flow from the upper end of said froth separating compartment into said pulp receiving compartment.

6. A flotation cell, as set forth in claim 4; wherein said screen member comprises an antieddy water grate extending horizontally between the walls of said froth separating compartment; and wherein downwardly inclined louvers are mounted across the opening in said intermediate wall to direct the pulp discharged from the pulp receiving compartment downwardly at an angle into the bottom portion of the froth separating compartment.

ADOLPHE ZARN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 953,746 Hoover Apr. 5, 1910 l,341,024= Seale et al May 25, 1920 1,394,306 Hynes Oct. 18, 1921 1,505,324 Eberenz Aug. 19, 1924 1,761,136 Lord June 3, 1930 2,063,751 Patek Dec. 8, 1936 2,167,788 Weinig Aug. 1, 1939 2,393,976 Daman et a1. Feb. 5, 1946 2,413,015 Wigton Dec. 24, 1946 2 ,423,456 Logue July 8, 1947 

